Canon R3 vs Sony A7S III

The Canon EOS R3 and the Sony Alpha 7S III are two professional cameras that were announced, respectively, in September 2021 and July 2020. Both the R3 and the A7S III are mirrorless interchangeable lens cameras that are equipped with a full frame sensor. The Canon has a resolution of 24 megapixels, whereas the Sony provides 12 MP.

Below is an overview of the main specs of the two cameras as a starting point for the comparison.

Headline Specifications

Canon R3		Sony A7S III
Mirrorless system camera		Mirrorless system camera
Canon RF mount lenses		Sony E mount lenses
24 MP – Full Frame sensor		12 MP – Full Frame sensor
6K/60p Video		4K/120p Video
ISO 100-51,200 (50 - 204,800)		ISO 80-102,400 (40 - 409,600)
Electronic viewfinder (5760k dots)		Electronic viewfinder (9440k dots)
3.2" LCD – 4150k dots		3.0" LCD – 1440k dots
Swivel touchscreen		Swivel touchscreen
12 shutter flaps per second		10 shutter flaps per second
In-body stabilization		In-body stabilization
Weathersealed body		Weathersealed body
760 shots per battery charge		600 shots per battery charge
150 x 143 x 87 mm, 1015 g		127 x 97 x 81 mm, 699 g

Check R3 price at
amazon.com
Check A7S III price at
amazon.com

Going beyond this snapshot of core features and characteristics, what are the differences between the Canon EOS R3 and the Sony Alpha 7S III? Which one should you buy? Read on to find out how these two cameras compare with respect to their body size, their imaging sensors, their shooting features, their input-output connections, and their reception by expert reviewers.

Body comparison

The physical size and weight of the Canon R3 and the Sony A7S III are illustrated in the side-by-side display below. The two cameras are presented according to their relative size. Three consecutive views from the front, the top, and the rear side are shown. All width, height and depth dimensions are rounded to the nearest millimeter.

If the front view area (width x height) of the cameras is taken as an aggregate measure of their size, the Sony A7S III is considerably smaller (43 percent) than the Canon R3. Moreover, the A7S III is markedly lighter (31 percent) than the R3. In this context, it is worth noting that both cameras are splash and dust-proof and can, hence, be used in inclement weather conditions or harsh environments.

The above size and weight comparisons are to some extent incomplete since they do not consider the interchangeable lenses that both of these cameras require. Hence, you might want to study and compare the specifications of available lenses in order to get the full picture of the size and weight of the two camera systems.

Concerning battery life, the R3 gets 760 shots out of its Canon LP-E19 battery, while the A7S III can take 600 images on a single charge of its Sony NP-FZ100 power pack. As can be seen in the images above, the R3 has a battery grip built in. This facilitates image-taking in portrait orientation and gives it additional battery power. In order to provide similar functionality for the A7S III, Sony provides the VG-C3EM vertical grip as an optional accessory (see here on ebay). The battery packs of both cameras can be charged via USB, which can be very convenient when travelling.

The following table provides a synthesis of the main physical specifications of the two cameras and other similar ones. If you want to switch the focus of the display and review another camera pair, you can move across to the CAM-parator tool and choose from the broad selection of possible camera comparisons there.

Body Specifications

		Camera Model	Camera Width	Camera Height	Camera Depth	Camera Weight	Battery Life	Weather Sealing	Camera Launch	Launch Price (USD)	Street Price
1.		Canon R3	150 mm	143 mm	87 mm	1015 g	760	Y	Sep 2021	5,999	amazon.com
2.		Sony A7S III	127 mm	97 mm	81 mm	699 g	600	Y	Jul 2020	3,499	amazon.com
3.		Canon 1D X Mark II	158 mm	168 mm	83 mm	1530 g	1210	Y	Feb 2016	5,999	ebay.com
4.		Canon 1D X Mark III	158 mm	168 mm	83 mm	1440 g	2850	Y	Jan 2020	6,499	amazon.com
5.		Canon 5D Mark II	152 mm	114 mm	75 mm	850 g	850	Y	Sep 2008	3,499	ebay.com
6.		Canon 5D Mark III	152 mm	116 mm	76 mm	950 g	950	Y	Mar 2012	3,499	ebay.com
7.		Canon R5	138 mm	98 mm	88 mm	738 g	320	Y	Jul 2020	3,899	amazon.com
8.		Canon R6	138 mm	98 mm	88 mm	680 g	360	Y	Jul 2020	2,499	amazon.com
9.		Canon R6 Mark II	138 mm	98 mm	88 mm	670 g	450	Y	Nov 2022	2,499	amazon.com
10.		Leica SL2-S	146 mm	107 mm	83 mm	931 g	510	Y	Dec 2020	4,895	amazon.com
11.		Sony A7R III	127 mm	96 mm	74 mm	650 g	650	Y	Oct 2017	3,199	ebay.com
12.		Sony A7R IV	129 mm	96 mm	78 mm	665 g	670	Y	Jul 2019	3,499	ebay.com
13.		Sony A7R IVA	129 mm	96 mm	78 mm	665 g	670	Y	Apr 2021	3,499	amazon.com
14.		Sony A7S II	127 mm	96 mm	60 mm	627 g	370	Y	Sep 2015	2,999	ebay.com
15.		Sony A9 II	129 mm	96 mm	76 mm	678 g	690	Y	Oct 2019	4,499	amazon.com
16.		Sony A850	156 mm	117 mm	82 mm	895 g	880	Y	Aug 2009	1,999	ebay.com
17.		Sony A900	156 mm	117 mm	82 mm	895 g	880	Y	Sep 2008	2,999	ebay.com
Note: Measurements and pricing do not include easily detachable parts, such as add-on or interchangeable lenses or optional viewfinders.
Convert to Imperial

The price is, of course, an important factor in any camera decision. The listed launch prices provide an indication of the market segment that the manufacturer of the cameras have been targeting. The A7S III was launched at a markedly lower price (by 42 percent) than the R3, which puts it into a different market segment. Usually, retail prices stay at first close to the launch price, but after several months, discounts become available. Later in the product cycle and, in particular, when the replacement model is about to appear, further discounting and stock clearance sales often push the camera price considerably down.

Sensor comparison

The size of the sensor inside a digital camera is one of the key determinants of image quality. A large sensor will generally have larger individual pixels that offer better low-light sensitivity, provide wider dynamic range, and have richer color-depth than smaller pixels in a sensor of the same technological generation. Moreover, a large sensor camera will give the photographer more control over depth-of-field in the image and, thus, the ability to better isolate a subject from the background. On the downside, larger sensors tend to be more expensive and lead to bigger and heavier cameras and lenses.

Both cameras under consideration feature a full frame sensor, but their sensors differ slightly in size. The sensor area in the A7S III is 2 percent smaller. They nevertheless have the same format factor of 1.0. Both cameras have a native aspect ratio (sensor width to sensor height) of 3:2.

With 24MP, the R3 offers a higher resolution than the A7S III (12MP), but the R3 has smaller individual pixels (pixel pitch of 6.00μm versus 8.40μm for the A7S III). However, the R3 is a somewhat more recent model (by 1 year and 1 month) than the A7S III, and its sensor might have benefitted from technological advances during this time that enhance the light gathering capacity of its pixels.

The resolution advantage of the Canon R3 implies greater flexibility for cropping images or the possibility to print larger pictures. The maximum print size of the R3 for good quality output (200 dots per inch) amounts to 30 x 20 inches or 76.2 x 50.8 cm, for very good quality (250 dpi) 24 x 16 inches or 61 x 40.6 cm, and for excellent quality (300 dpi) 20 x 13.3 inches or 50.8 x 33.9 cm. The corresponding values for the Sony A7S III are 21.2 x 14.2 inches or 53.8 x 36 cm for good quality, 17 x 11.3 inches or 43.1 x 28.8 cm for very good quality, and 14.1 x 9.4 inches or 35.9 x 24 cm for excellent quality prints.

The Canon EOS R3 has a native sensitivity range from ISO 100 to ISO 51200, which can be extended to ISO 50-204800. The corresponding ISO settings for the Sony Alpha 7S III are ISO 80 to ISO 102400, with the possibility to increase the ISO range to 40-409600.

In terms of underlying technology, the R3 is build around a Stacked BSI-CMOS sensor, while the A7S III uses a BSI-CMOS imager. Both cameras use a Bayer filter for capturing RGB colors on a square grid of photosensors. This arrangement is found in most digital cameras.

Consistent information on actual sensor performance is available from DXO Mark for many cameras. This service assesses and scores the color depth ("DXO Portrait"), dynamic range ("DXO Landscape"), and low-light sensitivity ("DXO Sports") of camera sensors, and also publishes an overall camera score. Of the two cameras under review, the R3 has a notably higher overall DXO score than the A7S III (overall score 10 points higher), which gives it an advantage in terms of imaging quality. This advantage is based on 1.3 bits higher color depth, 0.8 EV in additional dynamic range, and 0.7 stops in additional low light sensitivity. The table below summarizes the physical sensor characteristics and sensor quality findings and compares them across a set of similar cameras.

Sensor Characteristics

		Camera Model	Sensor Class	Resolution (MP)	Horiz. Pixels	Vert. Pixels	Video Format	DXO Portrait	DXO Landscape	DXO Sports	DXO Overall
1.		Canon R3	Full Frame	24.0	6000	4000	6K/60p	25.0	14.7	4086	96
2.		Sony A7S III	Full Frame	12.0	4240	2832	4K/120p	23.7	13.9	2520	86
3.		Canon 1D X Mark II	Full Frame	20.0	5472	3648	4K/60p	24.1	13.5	3207	88
4.		Canon 1D X Mark III	Full Frame	20.0	5472	3648	4K/60p	24.2	14.5	3248	91
5.		Canon 5D Mark II	Full Frame	21.0	5616	3744	1080/30p	23.7	11.9	1815	79
6.		Canon 5D Mark III	Full Frame	22.1	5760	3840	1080/30p	24.0	11.7	2293	81
7.		Canon R5	Full Frame	44.8	8192	5464	8K/30p	25.3	14.6	3042	95
8.		Canon R6	Full Frame	20.0	5472	3648	4k/60p	24.2	14.3	3394	90
9.		Canon R6 Mark II	Full Frame	24.0	6000	4000	4k/60p	25.4	14.6	3154	96
10.		Leica SL2-S	Full Frame	24.0	6000	4000	4K/60p	25.2	14.1	3504	95
11.		Sony A7R III	Full Frame	42.2	7952	5304	4K/30p	26.0	14.7	3523	100
12.		Sony A7R IV	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
13.		Sony A7R IVA	Full Frame	60.2	9504	6336	4K/30p	26.0	14.8	3344	99
14.		Sony A7S II	Full Frame	12.0	4240	2832	4K/30p	23.6	13.3	2993	85
15.		Sony A9 II	Full Frame	24.0	6000	4000	4K/30p	25.0	14.0	3434	93
16.		Sony A850	Full Frame	24.4	6048	4032	none	23.8	12.2	1415	79
17.		Sony A900	Full Frame	24.4	6048	4032	none	23.7	12.3	1431	79
Note: DXO values in italics represent estimates based on sensor size and age.

Many modern cameras cannot only take still pictures, but also record videos. Both cameras under consideration have a sensor with sufficiently fast read-out times for moving pictures, but the R3 provides a higher video resolution than the A7S III. It can shoot video footage at 6K/60p, while the Sony is limited to 4K/120p.

Feature comparison

Beyond body and sensor, cameras can and do differ across a range of features. The two cameras under review are similar with respect to both having an electronic viewfinder. However, the one in the A7S III offers a substantially higher resolution than the one in the R3 (9440k vs 5760k dots). The adjacent table lists some of the other core features of the Canon R3 and Sony A7S III along with similar information for a selection of comparators.

Core Features

		Camera Model	Viewfinder (Type or 000 dots)	Control Panel (yes/no)	LCD Specifications (inch/000 dots)	LCD Attach- ment	Touch Screen (yes/no)	Max Shutter Speed *	Max Shutter Flaps *	Built-in Flash (yes/no)	Built-in Image Stab
1.		Canon R3	5760	Y	3.2 / 4150	swivel	Y	1/8000s	12.0/s	n	Y
2.		Sony A7S III	9440	n	3.0 / 1440	swivel	Y	1/8000s	10.0/s	n	Y
3.		Canon 1D X Mark II	optical	Y	3.2 / 1620	fixed	Y	1/8000s	16.0/s	n	n
4.		Canon 1D X Mark III	optical	Y	3.2 / 2100	fixed	Y	1/8000s	20.0/s	n	n
5.		Canon 5D Mark II	optical	Y	3.0 / 920	fixed	n	1/8000s	3.9/s	n	n
6.		Canon 5D Mark III	optical	Y	3.2 / 1040	fixed	n	1/8000s	6.0/s	n	n
7.		Canon R5	5760	Y	3.2 / 2100	swivel	Y	1/8000s	12.0/s	n	Y
8.		Canon R6	3690	n	3.0 / 1620	swivel	Y	1/8000s	12.0/s	n	Y
9.		Canon R6 Mark II	3690	n	3.0 / 1620	swivel	Y	1/8000s	12.0/s	n	Y
10.		Leica SL2-S	5760	Y	3.2 / 2100	fixed	Y	1/8000s	20.0/s	n	Y
11.		Sony A7R III	3686	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
12.		Sony A7R IV	5760	n	3.0 / 1440	tilting	Y	1/8000s	10.0/s	n	Y
13.		Sony A7R IVA	5760	n	3.0 / 2340	tilting	Y	1/8000s	10.0/s	n	Y
14.		Sony A7S II	2400	n	3.0 / 1229	tilting	n	1/8000s	5.0/s	n	Y
15.		Sony A9 II	3686	n	3.0 / 1440	tilting	Y	1/8000s	20.0/s	n	Y
16.		Sony A850	optical	Y	3.0 / 922	fixed	n	1/8000s	3.0/s	n	Y
17.		Sony A900	optical	Y	3.0 / 922	fixed	n	1/8000s	5.0/s	n	Y
Note: *) Information refers to the mechanical shutter, unless the camera only has an electronic one.

One feature that is present on the R3, but is missing on the A7S III is a top-level LCD. While being, of course, smaller than the rear screen, the control panel conveys some of the essential shooting information and can be convenient for quick and easy settings verification.

The reported shutter speed information refers to the use of the mechanical shutter. Yet, some cameras only have an electronic shutter, while others have an electronic shutter in addition to a mechanical one. In fact, both cameras under consideration feature an electronic shutter, which makes completely silent shooting possible. However, this mode is less suitable for photographing moving objects (risk of rolling shutter) or shooting under artificial light sources (risk of flickering).

The Canon R3 has an intervalometer built-in. This enables the photographer to capture time lapse sequences, such as flower blooming, a sunset or moon rise, without purchasing an external camera trigger and related software.

The R3 writes its imaging data to CFexpress (type B) or SDXC cards, while the A7S III uses CFexpress (type A) or SDXC cards. Both cameras feature dual card slots, which can be very useful in case a memory card fails. Moreover, both cameras support UHS-II cards (Ultra High Speed data transfer of up to 312 MB/s).

Connectivity comparison

For some imaging applications, the extent to which a camera can communicate with its environment can be an important aspect in the camera decision process. The table below provides an overview of the connectivity of the Canon EOS R3 and Sony Alpha 7S III and, in particular, the interfaces the cameras (and selected comparators) provide for accessory control and data transfer.

Input-Output Connections

		Camera Model	Hotshoe Port	Internal Mic / Speaker	Microphone Port	Headphone Port	HDMI Port	USB Port	WiFi Support	NFC Support	Bluetooth Support
1.		Canon R3	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
2.		Sony A7S III	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
3.		Canon 1D X Mark II	Y	mono / mono	Y	Y	mini	3.0	-	-	-
4.		Canon 1D X Mark III	Y	mono / mono	Y	Y	mini	3.1	Y	-	Y
5.		Canon 5D Mark II	Y	mono / mono	Y	-	mini	2.0	-	-	-
6.		Canon 5D Mark III	Y	mono / mono	Y	Y	mini	2.0	-	-	-
7.		Canon R5	Y	mono / mono	Y	Y	micro	3.2	Y	-	Y
8.		Canon R6	Y	mono / mono	Y	Y	micro	3.2	Y	-	Y
9.		Canon R6 Mark II	Y	stereo / mono	Y	Y	micro	3.2	Y	-	Y
10.		Leica SL2-S	Y	stereo / mono	Y	Y	full	3.2	Y	-	Y
11.		Sony A7R III	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
12.		Sony A7R IV	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
13.		Sony A7R IVA	Y	stereo / mono	Y	Y	micro	3.2	Y	Y	Y
14.		Sony A7S II	Y	stereo / mono	Y	Y	micro	2.0	Y	Y	-
15.		Sony A9 II	Y	stereo / mono	Y	Y	micro	3.1	Y	Y	Y
16.		Sony A850	Y	- / -	-	-	mini	2.0	-	-	-
17.		Sony A900	Y	- / -	-	-	mini	2.0	-	-	-

Studio photographers will appreciate that the Canon R3 (unlike the A7S III) features a PC Sync socket, so that professional strobe lights can be controlled by the camera.

Both the R3 and the A7S III are recent models that are part of the current product line-up. The A7S III replaced the earlier Sony A7S II, while the R3 does not have a direct predecessor. Further information on the features and operation of the R3 and A7S III can be found, respectively, in the Canon R3 Manual (free pdf) or the online Sony A7S III Manual.

Review summary

So what is the bottom line? Is the Canon R3 better than the Sony A7S III or vice versa? Below is a summary of the relative strengths of each of the two contestants.

Advantages of the Canon EOS R3:

• More detail: Offers more megapixels (24 vs 12MP) with a 41% higher linear resolution.
• Better image quality: Scores markedly higher (10 points) in the DXO overall assessment.
• Richer colors: Generates images with noticeably better colors (1.3 bits more color depth).
• More dynamic range: Captures a larger spectrum of light and dark details (0.8 EV of extra DR).
• Better low-light sensitivity: Requires less light for good images (0.7 stops ISO advantage).
• Better video: Provides higher definition movie capture (6K/60p vs 4K/120p).
• Easier setting verification: Features an LCD display on top to control shooting parameters.
• Larger screen: Has a bigger rear LCD (3.2" vs 3.0") for image review and settings control.
• More detailed LCD: Has a higher resolution rear screen (4150k vs 1440k dots).
• Faster burst: Shoots at higher frequency (12 vs 10 flaps/sec) to capture the decisive moment.
• Easier time-lapse photography: Has an intervalometer built-in for low frequency shooting.
• More portrait friendly: Features an integrated vertical grip for easier portrait shooting.
• Longer lasting: Can take more shots (760 versus 600) on a single battery charge.
• Better studio light control: Has a PC Sync socket to connect to professional strobe lights.
• More modern: Is somewhat more recent (announced 1 year and 1 month after the A7S III).

Arguments in favor of the Sony Alpha 7S III:

• More detailed viewfinder: Has higher resolution electronic viewfinder (9440k vs 5760k dots).
• Larger viewfinder image: Features a viewfinder with a higher magnification (0.91x vs 0.76x).
• More compact: Is smaller (127x97mm vs 150x143mm) and will fit more readily into a bag.
• Less heavy: Has a lower weight (by 316g or 31 percent) and is thus easier to take along.
• More solid recording: Has a full-sized HDMI port for a sturdy connection to an external recorder.
• More affordable: Was introduced into a lower priced category (42 percent cheaper at launch).
• More heavily discounted: Has been on the market for longer (launched in July 2020).

If the count of individual advantages (bullet points above) is taken as a guide, the R3 is the clear winner of the match-up (15 : 7 points). However, the relative importance of the various individual camera aspects will vary according to personal preferences and needs, so that you might like to apply corresponding weights to the particular features before making a decision on a new camera. A professional wedding photographer will view the differences between cameras in a way that diverges from the perspective of a travel photog, and a person interested in cityscapes has distinct needs from a macro shooter. Hence, the decision which camera is best and worth buying is often a very personal one.

How about other alternatives? Do the specifications of the Canon R3 and the Sony A7S III place the cameras among the top in their class? Find out in the latest Best Mirrorless Interchangeable Lens Camera listing whether the two cameras rank among the cream of the crop.

In any case, while the specs-based evaluation of cameras can be instructive in revealing their potential as photographic tools, it says little about, for example, the shooting experience and imaging performance of the R3 and the A7S III in practical situations. User reviews that are available, for instance, at amazon can sometimes shed light on these issues, but such feedback is all too often partial, inconsistent, and inaccurate.

Expert reviews

This is why hands-on reviews by experts are important. The adjacent summary-table relays the overall verdicts of several of the most popular camera review sites (amateurphotographer [AP], cameralabs [CL], digitalcameraworld [DCW], dpreview [DPR], ephotozine [EPZ], photographyblog [PB]). As can be seen, the professional reviewers agree in many cases on the quality of different cameras, but sometimes their assessments diverge, reinforcing the earlier point that a camera decision is often a very personal choice.

Expert Camera Reviews

		Camera   Model	AP   score	CL   score	DCW   score	DPR   score	EPZ   score	PB   score	Camera Launch	Launch Price (USD)	Street Price
1.		Canon R3	5/5	o	4.5/5	..	5/5	4.5/5	Sep 2021	5,999	amazon.com
2.		Sony A7S III	4.5/5	+ +	5/5	91/100	4.5/5	5/5	Jul 2020	3,499	amazon.com
3.		Canon 1D X Mark II	..	..	4.5/5	89/100	4.5/5	4.5/5	Feb 2016	5,999	ebay.com
4.		Canon 1D X Mark III	..	+ +	5/5	..	4.5/5	4/5	Jan 2020	6,499	amazon.com
5.		Canon 5D Mark II	4/5	91/100	..	79/100	4/5	..	Sep 2008	3,499	ebay.com
6.		Canon 5D Mark III	..	+ +	..	82/100	4.5/5	4.5/5	Mar 2012	3,499	ebay.com
7.		Canon R5	4.5/5	+	4/5	91/100	4.5/5	4.5/5	Jul 2020	3,899	amazon.com
8.		Canon R6	5/5	+ +	4/5	90/100	4.5/5	5/5	Jul 2020	2,499	amazon.com
9.		Canon R6 Mark II	5/5	+ +	4.5/5	91/100	4.5/5	5/5	Nov 2022	2,499	amazon.com
10.		Leica SL2-S	4/5	..	4/5	..	4.5/5	4.5/5	Dec 2020	4,895	amazon.com
11.		Sony A7R III	..	+ +	4/5	90/100	4.5/5	5/5	Oct 2017	3,199	ebay.com
12.		Sony A7R IV	5/5	+	4.5/5	91/100	4.5/5	5/5	Jul 2019	3,499	ebay.com
13.		Sony A7R IVA	5/5	+	4.5/5	91/100	4.5/5	5/5	Apr 2021	3,499	amazon.com
14.		Sony A7S II	5/5	+	..	..	4.5/5	5/5	Sep 2015	2,999	ebay.com
15.		Sony A9 II	..	..	5/5	90/100	5/5	5/5	Oct 2019	4,499	amazon.com
16.		Sony A850	3/5	..	..	75/100	..	4.5/5	Aug 2009	1,999	ebay.com
17.		Sony A900	..	+ +	..	+ +	4.5/5	5/5	Sep 2008	2,999	ebay.com
Note: (+ +) highly recommended; (+) recommended; (o) reviewed; (..) not available.

Care should be taken when interpreting the review scores above, though. The assessments were made in relation to similar cameras of the same technological generation. A score, therefore, has to be seen in close connection to the price and market introduction time of the camera, and rating-comparisons among cameras that span long time periods or concern very differently equipped models make little sense. It should also be noted that some of the review sites have over time altered the way they render their verdicts.

Check R3 price at
amazon.com
Check A7S III price at
amazon.com

Other camera comparisons

Did this review help to inform your camera decision process? In case you would like to check on the differences and similarities of other camera models, just use the search menu below. As an alternative, you can also directly jump to any one of the listed comparisons that were previously generated by the CAM-parator tool.

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